This document discusses risk and expected rate of return in investments. It defines risk as the level of uncertainty associated with an expected outcome like rate of return. Investors prefer lower risk for a given expected return. There is a tradeoff between risk and return, with more aggressive investors willing to take on higher risk for higher return. Infrastructure projects generally have large investments, long timelines, low returns but high risk. Risk in investments can be measured by variance and is a key factor in financial decisions.